1. Field of the Invention
The present invention relates to a silicon carbide nanocomposite structure and a method of preparing the same, and more particularly, to a porous silicon carbide nanocomposite structure comprising nanowires which is self-formed on the surface of a porous body and in the internal pores thereof, and a method of preparing the same.
2. Description of the Related Art
In general, silicon carbide has low density and thermal expansion coefficient, and high melting point, strength, and hardness due to covalent bonds. Therefore, silicon carbide has excellent thermal stability and mechanical properties and thus has been widely used not only as a catalyst support working at high temperature, an adsorbent, or a filter for removing automobile exhaust fumes or filtering dust particles, but also as an abrasive material due to high hardness.
Silicon carbide has high strength, excellent chemical stability, and excellent electrical characteristics and thus may be used under an environment of high temperature and high voltage. However, since silicon carbide is sintering-resistant, it is not easily sintered even when being subjected to heat treatment at high temperature, and thus, there is a problem in that a silicon carbide material has cracks by stress during cooling, which reduces strength. Therefore, in order to make the material have porosity, a porous body is manufactured using a template, or a honeycomb structure in which a plurality of honeycomb segments are bonded to one another is prepared and used as a filter. As another method, a robust porous silicon carbide material is also prepared by binding silicon carbide particles at high temperature using a necking agent, and performing sintering.
Meanwhile, since a silicon carbide porous body is obtained by heat treatment at high temperature, nanopores disappear during heat treatment and thus it is difficult to obtain a nano porous body, and accordingly, a macro porous body having a low specific surface area is easily obtained. Therefore, the present invention prepares a silicon carbide nanocomposite structure comprising nanowires in which nanowires are self-formed on the surface of and the inside of the silicon carbide porous body, as means for enhancing the specific surface area.
Studies have been conducted on formation of silicon carbide nanowires in a silicon carbide porous body. However, said silicon carbide nanowires need to be synthesized through carbothermal reduction of carbon and silicon dioxide at 1,300° C. to 1500° C. for a long time, and thus it is difficult to achieve commercialization due to an increase in preparation costs.
In order to overcome these drawbacks, studies have been conducted on reducing the reaction temperature by mixing nano-sized silicon powder and carbon powder as another method. However, in doing so, expensive nano-sized silicon powder and expensive carbon materials such as carbon nanotube, activated carbon, and the like need to be used, and thus there is a disadvantage that the product price is rapidly increased.
The present inventors have focused attention on a silicon carbide nanocomposite structure that easily forms nanowires on the surface of and the inside of a porous silicon carbide at low temperature.
That is, the present inventors have found that a catalytically active component may be supported more efficiently by deriving a condition under which Si—Al—O-based nanowires may be self-grown at low temperature in a porous silicon carbide base material, and by controlling the growth condition, thereby completing the present invention.